One-Pager
Flight Physiology
Gas laws, hypoxia and cabin altitude (FP-C); stressors, aircraft safety and CRM (FP-C and CCP-C)
Download one-page PDFLetter landscape, ready to print or keep with your notes
Gas laws
| Law | Rule | Example |
|---|---|---|
| Boyle | Volume rises as pressure falls | Pneumothorax, ETT cuff, stomach, air splints |
| Dalton | Total pressure = sum of partial pressures | O₂ stays 21%, PO₂ falls: altitude hypoxia |
| Fick | Diffusion rises with area and gradient, falls with thicker membrane | Pneumonia, COPD, edema: more hypoxia at altitude |
| Henry | Dissolved gas follows its partial pressure | Nitrogen bubbles: decompression sickness |
| Graham | High to low pressure; lighter gases faster | O₂ and CO₂ move between lungs, blood and cells |
| Charles, Gay-Lussac | Heat raises volume (Charles) or pressure (Gay-Lussac) | Cold: gas shrinks, O₂ cylinder pressure falls |
Trapped gas (Boyle)
- Expands on climb, shrinks on descent: body gas +38% at an 8,000 ft cabin; dry gas doubles by 18,000 ft
- Ears and sinuses block on descent, mostly below 6,000 ft: swallow, yawn, Valsalva
- Pneumothorax: chest tube with one-way valve before flight; watch for tension
- ETT cuff: manometer on climb and descent (about 20–30 cmH₂O), or saline fill
- PIP rises after climb: rule out ETT obstruction first, then tension pneumothorax
- Stomach: vent an NG or OG tube
- Air splints firm on climb, vacuum splints soften; reverse on descent; recheck pulses
Diving: DCS and gas embolism
- Symptoms within 48 h of a dive, especially after flying within 24 h of diving: decompression illness until proven otherwise (NASEMSO)
- Oxygen regardless of the SpO₂ to wash out inert gas (NASEMSO); Merck: 100% by close-fitting mask
- Serious DCS: isotonic IV crystalloid without glucose (Merck); alert and mild: oral fluids. NASEMSO: IV access, bolus as indicated
- Arterial gas embolism (breath-hold ascent, or air drawn into a central line): keep flat; Merck supine when unstable, NASEMSO left lateral; no head-down (Merck: not effective; NASEMSO: may worsen cerebral edema); 100% oxygen; recompression before anything nonessential
- Transport: sea-level cabin or the lowest safe altitude (Merck: under 2,000 ft unpressurized) to a hyperbaric-capable hospital
Hypoxia and TUC
| Type | Problem | Examples |
|---|---|---|
| Hypoxic | Too little O₂ reaches the blood | Altitude, airway obstruction, drowning |
| Hypemic | Blood cannot carry enough O₂ | Anemia, blood loss, CO poisoning |
| Stagnant | Flow too slow | Shock, heart failure, high G, cold |
| Histotoxic | Cells cannot use O₂ | Cyanide, alcohol, narcotics |
Insidious onset; euphoria is the most dangerous symptom. Anemia, shock and lung disease lower altitude tolerance.
| Altitude | Time of useful consciousness |
|---|---|
| 18,000 ft | 20–30 min |
| 25,000 ft | 3–5 min |
| 30,000 ft | 1–2 min |
| 35,000 ft | 30–60 sec |
| 40,000 ft | 15–20 sec |
Stresses of transport
| Stressor | Effect | Mitigate |
|---|---|---|
| Thermal | About 2 °C colder per 1,000 ft | Warm, insulate, monitor |
| Dry air | Dehydration, thick secretions | Humidified O₂, fluids |
| Noise | 80–102 dB (helicopter); no auscultation, missed alarms | Ear protection; watch SpO₂, ETCO₂, chest rise |
| Vibration | Fatigue, monitor artifact, loosened tubes | Pad and secure everything |
| Flicker | Rotor or strobe at 4–20/sec: vertigo, rare seizures | Shade; look away |
| Fatigue | Slow judgment, errors | Rest, duty limits, IMSAFE check |
| G forces | Takeoff shifts blood toward the tail; landing, toward the nose | Secure; watch BP. Fixed wing: head forward if high ICP, feet forward if hypovolemic |
Cabin altitude and oxygen
| Altitude | Pressure (mmHg) | Dry gas volume |
|---|---|---|
| Sea level | 760 | 1.0× |
| 6,000 ft | 609 | 1.25× |
| 8,000 ft | 565 | 1.35× |
| 10,000 ft | 523 | 1.45× |
| 18,000 ft | 380 | 2.0× |
- Helicopters are unpressurized; pressurized aircraft usually hold a 6,500–8,000 ft cabin (sea-level cabin = lower cruise)
- Decompression: slow >10 sec (most insidious), rapid 1–10 sec, explosive <1 sec (PHAK: <0.5 sec)
Around the aircraft
- Approach only when signaled, in the pilot's view
- Front quarter or side approach; never the rear or tail rotor
- Crouch; on a slope, approach from downslope
- Carry equipment low and horizontal; secure loose items
- Stay clear during rotor start-up and slow-down
- Landing zone: about 100 × 100 ft (per program), flat, firm, free of debris and wires; report hazards and wind; never aim lights at the aircraft
- Fire or police secure the zone and keep bystanders back
Crew resource management
- CRM: use all people, equipment and information; AMRM adds medical crew, dispatch and managers
- Skills: communication, assertiveness, situational awareness, decisions, teamwork, workload; brief and debrief
- Three to go, one to say no: pilot plus two medical crew; any one can decline; a pilot's decline overrides all
- Patient condition stays out of the go/no-go decision
- Preflight risk analysis: weather, terrain, landing zone, fuel, fatigue, prior turn-downs
- Sterile cockpit: taxi, takeoff, landing, and below 10,000 ft except cruise
Practice Flight Physiology questions free in your browser34 exam-style questions with rationales. No account or download needed.
Practice free in your browser2,450+ exam-style questions with rationales. No account, no ads. Also free on the App Store and Google Play.
Related one-pagers
- EMS Patient AssessmentScene to handoff for EMT and paramedic: XABCDE, history, GCS, reassessment, reports
- EMT By-Complaint Quick PagesWhat the EMT looks for, gives and calls ALS for, and where to transport, for common EMT complaints
- EMT: Soft-Tissue and Musculoskeletal TraumaBleeding control, impaled objects, eviscerations, amputations, splinting, traction splints, pelvic binders, crush and mechanism of injury
- EMS OperationsScene hazards, hazmat, infection control, ambulance and air operations, ICS, legal duties and privacy, at EMT scope
- Common EMS MedicationsClass, use, typical adult dose and key cautions for 21 prehospital drugs, with EMT-scope drugs marked
- Prehospital Stroke and STEMIStroke and LVO screens, last known well, destination, 12-lead, STEMI times, and aspirin and nitro cautions for EMT and paramedic
Sources
- Federal Aviation Administration. Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C). 2023. Chapter 4 (standard atmosphere, lapse rate), Chapter 7 (cabin pressurization, decompression, p. 7-35), Chapter 17 (Aeromedical Factors). Link
- FAA Civil Aerospace Medical Institute. Introduction to Aviation Physiology. FAA; posted 2022. Link
- International Board of Specialty Certification. Certified Flight Paramedic (FP-C) Candidate Handbook. Updated April 2026. Content outline and sample questions 2 and 3 (p. 13). Link
- International Board of Specialty Certification. Certified Critical Care Paramedic (CCP-C) Candidate Handbook. Updated April 2026. Link
- Binks A. Pulmonary Physiology for Pre-Clinical Students. 7.2: Fick's Law of Diffusion. Medicine LibreTexts (Virginia Tech Carilion School of Medicine). Link
- Federal Aviation Administration. Helicopter Flying Handbook (FAA-H-8083-21B). 2019. Chapter 8, Safety in and Around Helicopters, Figure 8-3; Chapter 12, Flicker Vertigo. Link
- Federal Aviation Administration. Advisory Circular 135-14B, Helicopter Air Ambulance Operations. March 26, 2015. Link
- Federal Aviation Administration. Advisory Circular 00-64, Air Medical Resource Management. September 22, 2005. Link
- 14 CFR § 135.100, Flight crewmember duties (sterile cockpit). Electronic Code of Federal Regulations via Cornell LII. Link
- 14 CFR § 135.617, Pre-flight risk analysis (helicopter air ambulance). Electronic Code of Federal Regulations via Cornell LII. Link
- 14 CFR § 25.841, Pressurized cabins. Electronic Code of Federal Regulations via Cornell LII. Link
- FAA Civil Aerospace Medical Institute. Acceleration in Aviation: G-Force (pilot safety brochure OK-24-1154). 2024. Link
- Merlin MA, et al. Critical Considerations for Fixed-Wing Air Medical Transports. JEMS. March 6, 2019. Link
- FAA Civil Aerospace Medical Institute. Hearing and Noise in Aviation (pilot safety brochure AM-400-98/3). Link
- Coker RK, Armstrong A, Church AC, et al. BTS Clinical Statement on air travel for passengers with respiratory disease. Thorax. 2022;77(4):329-350. doi:10.1136/thoraxjnl-2021-218110 Link
- Brendt P, Schnekenburger M, Paxton K, Brown A, Mendis K. Endotracheal tube cuff pressure before, during, and after fixed-wing air medical retrieval. Prehosp Emerg Care. 2013;17(2):177-180. doi:10.3109/10903127.2012.744787 Link
- LibreTexts Chemistry. Introductory Chemistry (CK-12), 14.4 Charles's Law. Link
- LibreTexts Chemistry. Introductory Chemistry (CK-12), 14.5 Gay-Lussac's Law. Link
- LibreTexts Chemistry. Introductory Chemistry (CK-12), 14.15 Diffusion and Effusion and Graham's Law. Link
- National Association of State EMS Officials (NASEMSO) Medical Directors Council. National Model EMS Clinical Guidelines, Version 3.0. March 2022 (Dive (SCUBA) Injury/Accidents). Link
- Moon RE. Decompression Sickness. Merck Manual Professional Version. Last updated June 2025. Link
- Moon RE. Arterial Gas Embolism. Merck Manual Professional Version. Last updated June 2025. Link